1. Field of the Invention
The present invention is directed to a sensor for measuring acoustic shockwave pulses and using a piezo-electric measuring membrane.
2. Description of the Related Art
Acoustic shockwave pulse sensors are useful in lithotripsy, for example, in disintegating kidney stones through the use of shockwaves.
A shockwave sensor is disclosed in German Published Application No. 34 37 976. The shockwave sensor is used for measuring pressure amplitudes of a shockwave pulse in a propagation medium, such as in water. An important application for such sensor is to measure the pressure at the focus of focused shockwaves. The German published application, however, does not disclose how the sensor is to be constructed outside of the propagation medium, for example, in a lithotripsy application referred to as "dry coupling" with the patient. Likewise not discussed are difficulties which arise due to incorrect measured values identified by the piezo-electric measuring membrane as a result of secondary causes, such as, for example, circulation of the propagating medium (i.e. water) by pumps or due to the flow of and/or waves in the propagating medium which arise from the transmission of the shockwave.
In German Published Application No. 33 28 051 is disclosed the use of shockwave tubes in lithotripsy.